backlight: Fix backlight limiting on spitz/corgi devices

On spitz (& similar) machines, if battery is running low, backlight
needs
to be limited to lower step.  Unfortunately, current code uses &= for
limiting, turning backlight off completely for some backlight settings.
Fix that.

Signed-off-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>

drivers/video/backlight/corgi_lcd.c

@@ -433,8 +433,9 @@ static int corgi_bl_update_status(struct backlight_device *bd)
 
 	if (corgibl_flags & CORGIBL_SUSPENDED)
 		intensity = 0;
-	if (corgibl_flags & CORGIBL_BATTLOW)
-		intensity &= lcd->limit_mask;
+
+	if ((corgibl_flags & CORGIBL_BATTLOW) && intensity > lcd->limit_mask)
+		intensity = lcd->limit_mask;
 
 	return corgi_bl_set_intensity(lcd, intensity);
 }